Basics of adsorption relating to term, characteristics and applications

1. ADSORPTION
Presented by: Anamika
Debbarma

2. ADSORPTION: BASICS
Adsorption can be defined as a process in which atoms or molecules
move from a bulk phase ( ie solid, liquid or gas ) onto a solid or liquid
surface.
In other words, it is adhesion of atoms, ions or molecules from a gas
liquid or dissolved solid to a surface.
Adsorbate – The substance which is adsorbed on the surface.
Adsorbent – The substance on which surface the adsorbate is adsorbed.

3. ADSORPTION:PRINCIPLE
Adsorption is a surface phenomenon & consequence of surface energy.
Surface of liquid or solid is in a state of strain which results in
unbalanced residual force at the surface thereby resulting higher surface
energy.
The surface of liquids/solids always have a tendency to attract & retain
the molecular species with which it comes in contact. This phenomenon
is known as adsorption.

4. TYPES OF ADSORPTION
Types of Adsorption Characteristics
Physical Adsorption (Physisorption) Unselective. Low energy of
adsorption.
Associative Chemical
Adsorption(Chemisorption)
Selective ,strongly dependent on
both gas & solid surface. Higher
energies of adsorption than those of
physisorption
Dissociative Chemical
Adsorption(Chemisorption)
Selective, strongly dependent on
both gas & solid surface. Higher
energies of adsorption than those of
physisorption.

5. FACTORS AFFECTING ADSORPTION
TEMPERATURE
PRESSURE
SURFACE AREA
ACTIVATION OF SOLID ADSORBENT
AGITATION
pH
CHARACTERISTICS OF ADSORBENT
DOSE OF ADSORBATE & ADSORBENT

6. LIST OF COMMERCIAL ADSORBENTS
ACTIVATED CARBON
SILICA GEL
ACTIVATED ALUMINA
SYNTHETIC ZEOLITE
CLAY
POLYMERS & RESINS

7. ADSORPTION ISOTHERM & ITS TYPES
ADSORTION ISOTHERM IS A MATHEMATICAL MODEL OR
FUNCTIONAL EXPRESSION TO DEPICT THE DISTRIBUTION
OF SOLUTE BETWEEN THE SOLID & LIQUID PHASE AT
EQUILIBRIUM AT A CONSTANT FIXED TEMPERATURE.
TYPES OF ADSORPTION ISOTHERMS :
LANGMUIR ISOTHERM
FREUNDLICH ISOTHERM

8. LANGMUIR ISOTHERM: BASED ON CERTAIN
ASSUMPTIONS:-
Each surface site can be singly occupied.
There are no lateral interactions between adsorbed species.
The enthalpy of adsorption is independent of surface coverage.
The energy of adsorption is constant thus creating homogeneity of
energy on the surface.
Equation of it-
qe =(abCe)/(1+bCe)
Where a=qmax (maximum adsorption)
b =constant

9. FREUNDLICH ISOTHERM:BASED ON TWO FACTORS:-
The lateral interaction between the adsorbed molecules.
The energetic surface heterogeneity.
Equation of it-
qe =Kf(Ce)^(1/2)
Where Kf & n are empirical constant and the Freundlich constant “n”
denotes the degree of favourability of adsorption

10. WASTE WATER TREATMENT TECHNIQUES
Ion-Exchange
Adsorption:-
Activated Carbon adsorbents
Carbon nanotubes adsorbents
Low-cost adsorbents
Bioadsorbents
Membrane Filtration:-
Ultrafiltration
Reverse Osmosis
Nanofiltration
Electrodialysis
Coagulation & Flocculation
Flotation
Electrochemical treatment

11. APPLICATIONS OF ADSORPTION
Effective in heterogeneous catalysis.
Effective in removing coloring material.
Effective as ion exchange resins.
Used as adsorption indicators.
Used in gas masks.
Used in dyeing of cloth.
Used as de-humidizers.

12. SCOPE OF ADSORPTION
Adsorption is now recognized as an effective and economic method
for heavy metal & organic pollutants from water &wastewater
treatment.
The adsorption process offers flexibility in design and operation and
in many cases will produce high-quality treated effluent. In addition,
because adsorption is sometimes reversible, adsorbents can be
regenerated by suitable desorption process.
Certain techniques like coagulation, filtration with coagulation,
precipitation, ozonation, adsorption, ion exchange, reverse osmosis
and advanced oxidation processes have been used for the removal of
organic pollutants from polluted water and wastewater.
These methods have been found to be limited, since they often
involve high capital and operational costs.

13. On the other hand ion exchange and reverse osmosis are more attractive
processes because the pollutant values can be recovered along with their
removal from the effluents.
Reverse osmosis, ion exchange and advanced oxidation processes do not
seem to be economically feasible because of their relatively high investment
and operational cost.
Among the possible techniques for water treatments, the adsorption process
by solid adsorbents shows potential as one of the most efficient methods for
the treatment and removal of organic contaminants in wastewater treatment.
Adsorption has advantages over the other methods because of simple design
and can involve low investment in term of both initial cost and land required.
The adsorption process is widely used for treatment of industrial wastewater
from organic and inorganic pollutants and meet the great attention from the
researchers.

14. Adsorption has advantages over the other methods because of simple
design and can involve low investment in term of both initial cost and land
required.
The adsorption process is widely used for treatment of industrial
wastewater from organic and inorganic pollutants and meet the great
attention from the researchers.

15. THANK YOU